Manufacture of organotin trimercaptides



United States Patent O 2,713,585 MANUFACTURE OF ORGAN OTINTRIMERCAPTIDES Chris E. Best, Franklin Township, Summit County, Ohio NoDrawing. Original application October 5, 1950, Serial No. 188,653.Divided and this application June 4, 1953, Serial No. 362,951

9 Claims. (Cl. 260-429) This invention relates to novel compounds whichare monoorganotin trimercaptides, which compounds are useful, interalia, as heat stabilizers in vinyl chloride polymers and copolymers.

SYNOPSIS OF THE INVENTION The compounds of this invention are embracedby the formula mum total of four innocuous structures such ascarboncarbon triple bonds, aliphatic carbon-carbon double bonds, etherlinkages, thioether linkages, carboxylic ester groups bonded to carbonatoms, fluorine atoms linked to carbon, and halogen atoms bonded toaromatic ring carbon atoms, and R2, independently in each occurrence,represents an organic radical consisting of from 1 to 22 carbon atoms,hydrogen, carbon-carbon single bonds, carbon-hydrogen bonds(optionally), aromatic ring carbon-carbon double bonds, and (alsooptionally) a maximum total of four innocuous structures such ascarbon-carbon triple bonds, aliphatic carbon-carbon double bonds,hydroxyl groups bonded to carbon, sulfhydryl groups bonded to carbon,ether linkages, thioether linkages, carboxylic ester groups bonded tocarbon atoms, carboxylic amide groups bonded to carbon atoms, fluorineatoms bonded to carbon atoms, halogen atoms bonded to aromatic ringcarbon atoms, and groups of the formula identical in any given number,enumerated innocuous group, radical R1 or R2.

The compounds may conveniently be prepared by reacting mercaptans of theformula RH-H (II) with organostannic acids of the formula R; n-OH (1H)2,713,585 Patented July 19, 1955 all under the notation given inconvention with Formula I above. Water is eliminated, with formation ofthe desired compounds (I).

THE SUBSTITUENTS R1 AND R2 The groups R1 and R2 in the formulae abovemay be interfere with the synthesis or existence of the compounds. Itwill be understood, of course, that the atoms in the radicals R1 and R2attached to the sulfur and tin atoms limit of 11 such double bonds inany radical), for instance alkyl, cycloalkyl, aryl, aralkyl, alkaryl andlike monovalent hydrocarbon radicals containing from 1 to 22 carbonatoms. Likewise these radicals, in addition to simple hydrocarbonstructure, may contain various other groupings which are suificientlylow in number, and of suificiently non-reactive character, as not tointerfere with the synthesis of the compounds of this invention.Structures which have been found innocuous and non-interfering in eitherof the radicals R1 and R are, inter alia, aliphatic ethylemc linkages(as sulfhydryl groups and carboxylic amide groups. Likewise, the radicalR2 may be linked through sulfur atoms to more than one organicsubstituted tin atom, in which case the radical R1 of Formula I willcontain a further group of the formula a. (Iv) wherein R3 is a divalentorganic radical criteria of the radicalRz as tions of the reaction,

satisfying the above defined, save in that R2 is monovalent, R1 and R2are as above defined, with the understanding that R2 may be furtherexpanded into structures involving Rs-linked branched and network chainssuch as illustrated, and n in each occurrence is an integer from 1 to apractical (there would be no theoretical) limit of 10. In general, ithas been found that from 1 to 4 of the innocuous groups set forth abovemay be present in each of the radicals R1 and R2 in the formulae above.

Of all the radicals coming within the ambit of R1 and R2 as abovedefined, the simple hydrocarbon radicals containing not more than acombined total of four nonaromatic ethylenic linkages and acetyleniclinkages will be preferred, as the starting materials for thesecompounds will be most readily accessible, and less complications willbe encountered in the synthetic steps leading to the compounds of thisinvention.

It has also been observed in the practice of this invention thattertiary mercaptans react less readily and completely than do othermercaptans in the formation of the compounding of this invention. Theresultant mercaptides therefore constitute a less preferred class ofcompounds in accordance with this invention, while neverthelessremaining within the ambit thereof.

It is to be understood, of course, that the radicals R1 and R2 in theirseveral occurrences need not be, and in many cases are not, identicalwith each other, but may be different radicals each individually comingunder the definition of such radicals as given above; and that apreparation in accordance with this invention need not be a purecompound but may be a mixture of compounds each coming under the generalFormula I above, such as would result, for instance, when startingmaterials were used which would supply mixtures of radicals, forinstance starting materials derived from natural sources or frompetroleum fractions.

THE PREPARATION OF THE COMPOUNDS OF THIS INVENTION A convenientsynthesis for the compounds of this invention involves the reactionwherein R1 and R2 are as defined above in connection with Formula I. Itwill be understood that the Formula III for the organostannic acid issomewhat idealized, since these compounds occur largely as pyro acids ofvarying degrees and complexity of condensation; however, the, v

pyro acids mercaptolize fairly readily under the condiwhich thereforeproceeds effectively as shown. In some preparationsof organostannicacid, the degree of condensation may be so high as to result in somewhatreduced yields, and it will be preferred to employ acids of a relativelylow degree of condensation. It is to be understood that in many casesthe three mercaptan molecules indicated by the notation HSRz areidentical mercaptan molecules, assuming that an unmixed mercaptan issupplied to the reaction; if a mixture of mercaptans is supplied to thereaction, these will distribute themselves, in accordance with thereactivities involved, between reactive engagements in which themercaptan molecules reacting with a given organostannic acid are allidentical, and those in which the mercaptan molecules are not allidentical (e. g. two alike and one dissimilar, or all three dissimilar)and are arranged at the several positions on the tin atom in variouscomplexions. In accordance with the notation above, the radicals R2 maythemselves contain thiol groups, i. e., the mercaptan (II) may have theformula HSR3SI-I as R3 is defined above in connection with Formula IV,in which case a greater or less proportion of the mercaptan (Ii) willreact with two organostannic acid molecules (III) resulting inreticulate structures such as indicated by Formula IV. The reaction isreadily and simply carried out by mixing the mercaptans (II) togetherwith the organostannic acid (III) and heating the mixture with stirringat temperatures in the range 40 C.l80 C. In most cases the mercaptanswill not be volatile under these conditions and the reaction may becarried out in open vessels; however, some of the lower mercaptans mayhave appreciable, or even superatmospheric vapor pressures at thesetemperatures, in which case the reaction may be carried out in closedvessels with provision for reflux and, if necessary to confine thereactants, maintenance of superatmospheric pressure. The reaction ismore'readily controlled if not all theorganostannic acid is added attheoutset, but rather is added in increments as the reaction proceeds. Thereactants will be used in substantially equivalent proportions, as thereaction is substantially quantitative; however to the extent that theproportionation may be inaccurate, the mercaptan should be used inexcess, as the organostannic acid is usually more expensive ingredientand, in the case of organostannic acids manufactured by certaintechniques devised by associates of the present patentees, will be lostalong with the salt which accompanies it as an incident of itsmanufacture. Economic or technical considerations may in many casesbring about a reversal of these recommendations in particular cases. Thereaction goes very rapidly, giving a good yield'almost instantly uponmixing, and going substantially to completion in the course of an houror so. The reaction may be carried out in the absence of a solvent,since the mercaptan employed will usually be a liquid, or at leastfusible at the temperature of reaction. Alternately, a suitablenonreactive solvent may be employed, such as hydrocarbon solvents on theorder of petroleum ether, benzene, toluene, xylene or the like, orchlorinated solvents such as carbon tetrachloride, trichloroethylene,tetrachloroethylene, hexachlorobutadiene, and the like. When a solventis employed, it may be evaporated out of the reaction mass to entrainand remove the water resulting from the reaction.

As noted above the radicals R1 and R2 are not critical in nature and maybevselected from a wide variety of substituents, examples of which arelisted. The radicals R2 are derived from the mercaptan or mercaptanssupplied to the reaction, while the radicals R1 are those attached tothe tin atomin the organostannic acid supplied to the reaction. Givenherewith are selected lists of mercaptans and organostannic acidsconforming to the requirements of the radicals R1 and R2 given above.Any one of these or similar mercaptans may be reacted with any of theseor similar stannones to yield compounds according to this invention.

T dble I M ercaptans:

Methyl mercaptan Butyl mercaptan Amyl mercaptan n-Hexyl mercaptan2-ethyl hexyl mercaptan tt-Octyl mercaptan Decyl mercaptan Dodecylmercaptan Mixed mercaptans derived from fatty radicals of cocoanut oilor other natural fatty oils Mercaptans from trimerized isopropyleneMercaptans containing the alkyl radicalsof'kerosene petroleum fractionsTridecyl mercaptan Oleyl mercaptan Thioabietinohor other mercaptansderived from the hydrocarbon residues'of naval stores products, talloil, etc.

Mer'capt'ans derived by conversion to mercaptans of the alcoholsproduced by the carbon monoxidehydrogen synthesis, duced by the oxoprocess or of the mixed alcohols pro- 6 n-Hexylstannic acid Z-ethylhexylstannic acid Laurylstannic acid Alkylstannic acid in which the alkylgroups are the Mercaptans produced by reduction of the alkyl sulmixedalkyl groups derived from cocoanut oil fonic acids resulting fromultraviolet-sulfuryl chlon-Hexadecyl stannic acid ride treatment ofparafiins Phenylstannic acid 2-mercaptoethanol a-Naphthyl stannic acid2(2-mercaptoethoxy) ethanol 2-thieny1 stannic acid 2-ethyl hexylthioglycolate Xenyl stannic acid Z-mercaptoethyl stearate Ethoxyethylstannic acid imerclaptoethytl stearamlde The compounds prepared inaccordance with this in- B li mercaptaan vention are for the most partliquids at ordinary temperenzy e b t atures, although some of them maybe solids. They are 22, 2 i f' f 9 f mepcap an 0 useful as intermediatesin the production of other com- 1 P enye er 1 pounds, and findparticular use as stabilizers in vinyl Thiophenol chloride resins. 0-,m, and p-Chlorothrophenol EXAMPLE I Thio-p-cresol G l a-Thionaphthol 2ram-mo e i h h 1 Mercaptan (per Table III) .3 Thiophenethiolorganostannic acid (per Table III) .1 Mercaptobenzimi dazole A series ofmonoorganotin trimercaptides was prepared Th IOS aIICYCIIC ac 1d byreacting together, in combinations set forth in Table Thloclmlamlc acldIII hereinbelow, .3 gram-mole portions of various merp q methylbel'lloate captans with .1 gram-mole portions of variousorganop-Bromothloph nol stannic acids. In each case the selectedmercaptan was p-Trlfillol'omethyl thlophenol placed in an open beakerand heated to 125 C. (In those cases where the mercaptan was volatile,e. g. butyl Table II v mercaptan, the reaction was carried out in aclosed ves- Organostannic acids: sel under reflux with a water trap,rather than in an open Methylstannic acid beaker.) The selectedorganostannic acid was then added Ethylstannic acid with continuousstirring, in small portions, as rapidly as Butylstannic acid the foamingwould permit. After all the organostannic Isobutylstannic acid acid hadbeen added, and foaming had subsided, the tem- Table III Constitution ofProduct Properties of Product Color of Test Specimen Alter Exposure inOven For- Amount At h ri T Att g T i b Run tac e 0 ac e 0 P 3' No.'IinInOrgauo- Sulfurln m. weight) 15 Min. 30 Min. Min. Min Min.

stannic Acid Mercaptan Used Used a. Butyl 1.6541 2.0 ofi-white.--. palestraw... 1 sec.amyl 1.5452 2.0 do straw 2 25 pale straw..- pale straw...3 Cocoauut 1.4975 .5 elf-whiten 4 1.0 do -5 2.0 white light tan 6t-dodecyl 2.0 pale straw... pale straw... brown 7 octadecyl 50-60 2.0ofi-whiteofi-white.-.- off-white. psglle fitrfidw, 8

at: e ge. alpha pinene 1.5449 2.0 .-...do straw straw straw 9 Methylmercaptan.-

Z-hgdroxy- 1.6168 2.0 faint straw.. light straw light straw....straiw,blaek 10 et e ge. alplllial naph- 1.71 2.0 ofl-white.-.. strawstraw -do 11 t y p-cresyl 143145 2.0 faint yellowpale straw... 0.......light brown... 12 methylbeuzo- 1.6579 2.0 pale straw... light tan. browndark brown... 13

ate. chlorobenzyl 1.6523 2.0 white white ofi-white.... pale straw.-...strawiblack 14 spo diphenyl-ether 2.0 faint yellow. faint yellow. yellowyellow muddy yel- 15 (Iithiol. low. Ethyl Oocoauut 1.4091 2.0 whitewhite white pale straw... 16 Butyl 1.5420 2.0 ofi-white ofi-white....light straw.. brown 17 Cocoanut 1.5009 2.0 white .-do. off-white...-pale straw-.- 18 Butyl t-Dodecyl viscousli 2.0 cream..- pale straw..-pale straw... brown 19 p-Cresyl 16540 2.0 white off-whiten straw lightbrown. 20 Iethylbenzostiff, resinous 2.0 light beige... light redlightbrown. brown 21 ate. product. dish brown. C Cocoanut 1. 4920 2.0ofi-white. ofl-white pale straw pale straw-.. straw 22 Oman p-Cresyl 2.0white ..do straw. dark brown. 23 Butyl 1.5710 2.0 -do. straw...-- straw,black. 24 Cocoanut 1.5124 2.0 oil-white. off-white off-white, 25 Pheny]black edges.

p-Cresyl 1. 6890 2.0 pale straw..- light tan black 26 Thienyl Cocoanut2.0 do dirtystraw. dirty tan dark brown- 27 Control with- 0 dark tam-.-brown dark brown do 28 out stabilizer.

1 These are mixed fatty radicals, consisting largely of lauryl andmyristyl, derived by reduction of the fatty acids of cocoanut oil.

1 This 15 the name 3 Recrystallized from heptane. Analysis mm of themercaptan employed, not the group attached to cated 18.93% sulfur asagain sulfur therein, as set out in the column heading.

st a theoretical 19.1% sulfur.

'pounds of this invention.

perature was raised to 150 C., held atthis point for 15 minutes, andthen reduced to 25 C. The cooled reaction mass was filtered to removeany unreacted material (in some cases, the organostannic acid containsinsoluble salts the filtration.)

The products were then tested as stabilizers in vinyl chloride resins asfollows: (The parts given are by weight.)

Parts Copolyrner of 97% vinyl chloride, 3% vinylidene chloride 100Di(2-ethylhexyl)phthalate 46 Tricalcium phosphate l Silicate pigment l.Stabilizer compound under test 2 A series of compositions was made upinaccordance with the foregoing schedule, using as the stabilizer eachof the organotin trimercaptides prepared as above described andtabulated below. In each case the listed ingredients, together with thecompound under test, in the proportions indicated in the schedule werethoroughly mixed together and placed on a laboratory roll mill at 320 F.Milling was continued for two minutes, at which time the gauge was setat .025 inch and the sheet removed from the mill and cooled.

Five one-inch square specimens of each of the sheets of each of thecompositions prepared as above described were hung vertically in aforced-draft oven maintained at 170 C. Specimens of each of thecompositions were removed after intervals of 15, 30, 60, 90 and 120minutes of exposure in the oven, and were rated subjectively as to colorand extent of deterioration by the operator, which ratings are set forthherewith in Table III opposite the tabulation of the preparation of thecom- By way of contrast, a' composition in accordance with the aboveformula, but omitting the stabilizer, showed marked deterioration afteras short a time as 15 minutes in the oven, see the last item in TableIII.

From the foregoing general discussion and detailed specific examples, itwill be evident that this .invention provides a novel series oforganotin trimercaptides which are readily prepared frominexpensiveand'abundantly available starting materials by the use of simplereacting an organostannic with amercaptan of the formula Rz-SH in whichformulae R1 represents an organic radical consisting of from 1 to 22carbon atoms, hydrogen, carboncarbon single bonds, carbon-hydrogenbonds, from 0 to 11 aromatic ring carbon-carbon double bonds, and from Oto 4 innocuous structures selected from the group consisting ofcarbon-carbon triple bonds, aliphatic carbon-carbon double bonds, etherlinkages, thioether linkages, carboxylic ester groups bonded to carbonatoms, fluorine atoms bonded to carbon atoms, and halogen atoms bondedto aromatic ring carbon atoms, and R2 represents an organic radicalconsisting of from 1 to 22 carbon atoms, hydrogen, carbon-carbon singlebonds, carbon-hydrogen bonds, from O to 11 aromatic ring carbon-carbondouble bonds, and from 0 to 4 innocuous structures selected from thegroup consisting of carboncarbon triple bonds, aliphatic carbon-carbondouble bonds, hydroxyl groups bonded to carbon, sulfhydryl groups bondedto carbon, ether linkages, thioether linkages, carboxylic ester groupsbonded to carbon and carboxylic amide groups bonded to carbon atoms.

2. Process which comprises reacting methylstannic acid with themercaptans derived from cocoanut oil fatty acids.

3. Process which comprises reacting butylstannic acid with themercaptans derived from cocoanut oil fatty acids.

4. Process which comprises reacting phenylstannic acid withthio-p-cresol.

5. Process which comprises reacting phenylstannic acid with themercaptans derived from cocoanut oil fatty acids.

6. Process which comprises reacting 2-thienyl stannic acid with themercaptans derived from cocoanut oil fatty acids.

7. Process which acid of the formula comprises heating an organostannicR-s n-OH with a'mercaptan of the formula R-S-I-I are members of thegroup References Cited in the file of this patent Backer et al., Rec.trav. chim. 53 1061 (1935). Organic Synthesis, vol. 21, page 36, line 6to line 5,

A page 37 (1941).

1. PROCESS WHICH COMPRISES REACTING AN ORGANOSTANNIC ACID OF THE FORMULA